Matter Effect on Neutrino Oscillation from Universality Violation in Neutral Current Interactions Naotoshi Okamura (YITP) and Minako Honda (Ochanomizu Univ.) Yee Kao (Virginia Tech.) Alexey Pronin (Virginia Tech.) Tatsu Takeuchi (Virginia Tech.) Irvine) based on hep-ph/ hep-ph/ hep-ph/0609xxx

Introduction

SM : universality of NC 1. Can interactions between neutrinos and matter due to New Physics have any effect on neutrino oscillations ? New Physics : “no” universality of NC : new source of potential -beam Motivation e-e- e-e- p p n n 2. Can such effects be measured experimentally and be used to constrain New Physics ?

Universality Violation in NCI beam Matter effect (b) neutral current interaction (a) charged current interaction etc... processes ex) MSSM with lead to the NC universality violation In a number of models beyond the SM, the universality of the couplings can be violated through radiative corrections.

LEP/ OPAL, DELPHI, L3, ALEPH, SLD NO CONSTRAINT individual decay CERN The experimental constraints 1 ~invisible decay width~ No information is available on the individual decay widths into each flavor invisible

LEP invisible decay width (total width is constrained.) cf ) Z couplings to charged leptons LEP/ OPAL, DELPHI, L3, ALEPH, SLD The experimental constraints 2 ~individual~ CHARM, CHARM CERN (’80s) Z couplings to neutrinos PLB180,303(1986), PLB320,203(1994)

The theoretical possibility of universality violation in many models The weakness of the current experimental bounds It would be interesting to analyze the effect of such a violation on neutrino oscillations. PLB180,303(1986), PLB320,203(1994) CHARM, CHARM II

New Physics that can contribute to neutrino oscillations: R-parity violating couplings Gauged B-(  L e +  L  +  L  )   Z’ in Topcolor assisted Technicolor Leptoquarks that couple different generations  etc. Direct exchange of New Particle e.g.)

Introduction Matter effect –effective potentials for neutrinos in matter W and Z exchange –effective Hamiltonian In the presence of NC universality violation Can we see ? (A hypothetical experiment) Fermilab NuMI beam ⇒ Hyper-Kamiokande detector (1Mt) Constraints on New Physics (e.g. leptoquarks) Summary Plan of Talk

Matter Effect (Effective Potential) the mixing angles the Probability

in ordinary matter The effective potentials (W & Z exchange) neutral current interaction charged current interaction

The effective Hamiltonian U:MNS matrix : measure of universality violation in NC ： effective mixing matrix ： effective mass-squares central value of CHARM CC NC derived from universality violation in Neutral Current interaction

effective mixing angles (normal hierarchy) (details in our paper)

effective mixing angles (inverted hierarchy) (details in our paper)

shift of effective mixing by  neutrinoanti-neutrino normal hierarchy is shifted by inverted hierarchy is shifted by Sum up the calculation, (details in our paper) In the region of

Survival Probability (  )

The oscillation probabilities ( L=9,120km ) neutrino beam energy [ GeV ] normal hierarchyinverted

The oscillation probabilities ( L=9,120km ) neutrino beam energy [ GeV ] normal hierarchy inverted hierarchy  atm <  /4

Can we measured experimentally ? one example (FNAL – HK)

to Japan small value (  ) large matter effect  high energy (E~O(10)GeV)  long base-line (L~O(10 4 )km) from J-PARC (Japan) USA-Japan

Fermilab HK (1Mt) 732km 9,120km ~732x12 Fermilab (NuMI) Hyper-Kamiokande [ L~9,120 km ] We can expect a non- negligible event rate even when oscillation is taken into account Main Fermilab 17GeV NuMI Beam (LOI) no oscillation

The expected number of HK neutrino beam energy [ GeV ] number of events oscillation dip 17GeV We can expect the green line to be clearly distinguishable from the blue or pink lines. after 5 years of data taking (1Mton)

The constrains on universality violation  %C.L. 95%C.L. 90%C.L. ~0.015~ year 3years 5years 10years much tighter constraints than that from CHARM and CHARMII  2 / 14dof (8GeV-22GeV)

Constraints on New Physics (e.g. Leptoquarks) S : scalar, V : vector, subscript : dim of SU(2) rep.    M LQ [TeV] S2S2 V3V3

 This result is highly sensitive to the value of sin 2 (2  23 ) Summary The violation effectsnormalinverted mixing angle oscillation probability L=9,120 km 17GeV We investigated the matter effect on neutrino oscillation from universality violation in neutral current interactions. Fermilab ⇒ Hyper-Kamiokande  If sin 2 (2  23 ) is NOT too close to 1, we may be able to either observe this effect, or impose a much tighter constraint on universality violation than that from CHARM and CHARMII.

Thank you very much for your attention

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